bio questions--origin of life on earth

Evan Webber
Period 1
1. Four processes that are needed for the spontaneous origin of life on Earth are the abiotic
synthesis of small, organic molecules, the synthesis of polymers from these monomers,
the packaging of polymers into protobiont droplets with a stable internal chemistry, and
the origin of self-replicating molecules.
2. Miller and Urey’s experiment simulated the conditions of a pre-biotic Earth. They used
H2O, H2, CH4, and NH3 to match the supposed atmosphere of the time. Sparks were
used to mimic lightning which provided the energy for chemical reactions that created
life to occur. They found that a number of amino acid and complex hydrocarbons, both
essential to life, had formed.
3. Comets can carry organic compounds. Earth was bombarded with comets and asteroids 4
billion years ago and the impacts could have helped polymerize amino acids into
4. The synthesis of organic compounds could have occurred in space, in alternating wet and
dry conditions, near volcanoes, and/or in deep oceans. Scientists created a low-pressure
and low-temperature environment to simulate space and synthesized amino acids. The
drying of clay particles in sea shores or flood plains of a river could have catalyzed
reactions to form early organic molecules. Stromatolites which are among the oldest
known fossils support the theory. Eruptions from volcanoes spit out water vapor, gases,
and minerals which could have formed organic matter. Those raw materials plus the heat
from volcanoes could have provided the necessary conditions to form amino acids and
sugars. In the ocean near thermal vents, hot water rises and picks up minerals along the
5. RNA can self-replicate without enzymes and it can act as a catalyst to help speed up
6. Coacervates are almost like living organisms. Living cells may have been preceded by
coacervates. They tend to be self-assemble when a suspension of polypeptides, nucleic
acids, etc. is shaken. Microspheres self-assemble, form a membrane store energy, etc.
7. About 3.5 billion years ago, some bacteria developed the ability to photosynthesize.
They helped convert iron dissolved in ocean water into precipitates of iron oxide (rustcolored) layers of rock. Since oxygen is the waste product of photosynthesis,
photosynthetic bacteria proliferated as the atmosphere became more oxygen-rich.
8. Endosymbiosis involves engulfing and incorporating another cell. Endosymbiotic theory
posits that early prokaryotes engulfed mitochondria which are thought to have once been
separate cells. Mitochondria have their own functioning DNA, so they are thought to
have acted without the control of the nucleus and thus been outside of the cell.